The present invention relates to a pulse generator, and more particularly to a pulse generator circuit employing a resolver for generating a train of pulses dependent on an angular displacement.
Conventional pulse generators employing resolvers for generating a series of pulses operates by generating a sine- or rectangular-wave excitation voltage signal from clock pulses, with a frequency-dividing counter, applying the excitation voltage signal to the primary winding of the resolver, counting, with a counter, the phase difference between the reference signal and an output generated from the secondary winding of the resolver, and issuing the output from the counter at a certain timing.
FIGS. 1 and 2 of the accompanying drawings illustrate a prior-art pulse generator circuit, in block form, and the waveforms of signals in the pulse generator circuit, respectively. As shown in FIG. 1, an input signal sin .omega.t applied to the primary winding of a resolver and a phase-modulated output signal sin (.omega.t+.theta.) issued from the secondary winding of the resolver are applied to an analog converter 21 which generates a phase-difference signal PH. The phase-difference signal PH and reference clock pulses CP are applied to an AND gate 22 which issues an output CPH to a counter 23 for counting applied pulses. The count value from the counter 23 is latched by a latch circuit 24 which delivers parallel signals to a parallel-to-serial converter circuit 25 for converting the applied parallel signals to a serial succession of pulses which is issued as an output.
FIG. 2 shows the waveforms of the input signal applied to the primary winding of the resolver, the output signal issued from the secondary winding of the resolver, the output from the comparator 21, and the output from the AND gate 22. More specifically, FIG. 2 illustrates at (A) the phase difference between the excitation signal sin t applied to the primary winding of the resolver and the phase-modulated signal sin (.omega.t+.theta.) issued from the secondary winding of the resolver. FIG. 2 shows at (B) the signal PH from the comparator 21, i.e., the rectangular-wave signal dependent on the phase difference. FIG. 2 shows at (C) reference clock pulses occurring during high-level intervals of the rectangular-wave signal PH. With the conventional arrangement shown in FIGS. 1 and 2, the anglular displacement .theta. is issued as an absolute anglular displacement. Therefore, if the frequency of the clock pulses is increased, then the number of output lines of the latch circuit 24 will have to be increased, resulting in a complicated circuit arrangement. Conversion from the parallel output to the serial output requires to be effected by the special processing circuit or converter circuit. Since the parallel-to-serial converter circuit is limited to a certain processing speed, the pulse generator circuit would be highly costly to construct if higher-speed operation were to be achieved.